Process of preparing cellulose



Patented Aug. 1, 1933 UNITED STATES PROCESS OF PREPARING CELLULOSE Antonio Bayarte Bori and Jos Martinez Estape, Habana, Cuba, assignors, by direct and mesne assignments, to said Estape No Drawing. Application May 14, 1931 Serial No. 537,490

16 Claims.

Our invention relates to the manufacture of.

cellulose, and is primarily concerned with the production of a cellulose of the highest quality,

such as alpha cellulose.

In order to prepare an alpha cellulose ofl% purity which is the product of this invention, itis necessary that the fibrous material be given a chemical treatment in a novel manner, and thereafterthe resultant pulp is subjected to an electrolytic eflect to obtain the desired alpha cellulose.

Furthermore, it is an important feature of this invention that we have discovered the valuable characteristics of certain canes which not only grow in abundance in the Island of Cuba, but are obtainable without need of cultivation and have the peculiar characteristic of multiplying each time a'harvest of the cane is,taken.

These canes from timeimmemorial, have been regarded as worthless and attempts have been made to completely destroy such growth.

We have found, however, that the purposes of obtaining a large amount of cellulose in good I quality, such canes have no equal, and we pro- 26-pose in the present invention to treat Castilla cane or Carrizo cane, known scientifically as Arimdo Donax; Guin cane, scientifically known as Gynerium Saccharoides; and Brava cane, scientifically known as Gynerium Sagittatum.

30 We also propose to treat other canes which have been found satisfactory for this p ose by us, namely Choix, Lachrima Jobi, Malacca Cane,

v Bamboo, Otate, Feathergrass, Henequen, Ramie,

etc.

in carrying out the invention, we prefer to use Castilla cane and'Brava cane, as well as Guin since we find that these produce cellulose of the most excellent quality and in commercially successful quantities.

40 The particular cane, either whole or chopped into pieces, is placed in a digester. In some cases we use cane of the same quality, while in other cases we use a mixture of one'or more of the canes listed above.

-Inthe digester thecaneiscookedinthepresence of a digesting liquor comprising one or more of such materials as sodium hydroxide or potassium hydroxide, sodiumsulphide, sodium acetate, and ammonia. As stated one or more'of' a further acetylation when acetyl-cellulose is to time of treatment may vary from as little as half an hour to five hours, as may be required.

The NaOH or ,KOH is introduced, in orderthat by its combination with the saponifiable matters of the canes, there will result soluble soaps which will be eliminated by; successive washings.

The NaaS combines with the lignin of the canes, giving sulphonic compounds which are also soluble, and therefore will be eliminated by wash- We use CHaCOONa in order that this'salt may change its sodium in-the ordinary way of the i, reaction, and the newly generated acetic anhydride may serve to prepare the molecule for be obtained. The chemicalnature of the cellulose of the type given by our canes, is very stable, showing a special difiiculty to the breaking of its molecules for the introduction of new atoms. Therefore, the production of acetyl-cellulose will be extremely difficult unless the pulp is given a previous treatment by this sodium acetate.

When the pulp obtained in the digester is destined to produce Intro-cellulose instead of acetyl-cellulose, then the sodium acetate must be leftout, such treatment being then to no purpose,

since the introduction of nitric groups into the molecule presents no special difliculty.

The ammonia which we have in our'formula serves to add alkalinity to that given by the a washing operation, such aswith steam or hot water or both. y We have found that the pulp resulting from this treatment with one or more of the reagents or digesting auxiliaries above referred to, is recovered in a most remarkable state of purity.

The pulp obtained in the digester through the action of the digesting liquor, as above recited, contains a percentage of cellulose of about 80% or even higher, depending on theconcentration of the digesting liquor and the time of treatment, and therefore needs no further treatment to be transformed into the so-called sulphite or soda pulps, since it has already the characteristics 0 the. said pulps and in a higher degree. m this connection. also, the recovered pulp may require bleaching in some cases, and any of smokeless powder.

I cellulose obtained from Brava cane is characordinary bleaching substance may be utilized, although we prefer a 3% solution of acetic acid or calcium hypochlorite, and accomplish the bleaching at a temperature of about 50 C. This bleaching operation may be conducted in the digester and the resultant cellulose freed from the bleaching solution may be expanded in any suitable manner. Thus, for instance, we propose to expand it by the very simple procedure of subjecting it to a draught of hot air or other inert medium.

As set forth above, unless the pulp recovered by the digesting and bleaching operations is satisfactory, we propose to modify it by a further chemical treatment or an electrolytic treatment to obtain a 100% pure alpha cellulose.

Thus, we may subject the pulp obtained from the digester to a purifying treatment with a digesting liquor of caustic potash (KOH) at 4%, for approximately an hour, and at the temperature of ebullition; then it is treated in-a bath of chloric acid at 1% (one percent), also for an hour and at the same temperature; and finally it is washed in a solution of ammonia. It could be washed with other substances such as water, but we have found an ammonia solution most effective to lower in the 'nitro-celluloses the residue of ashes required for the manufacture By the treatment described a 100% alpha cellulose is obtained.

In order to obtain the pure alpha cellulose by the chemical process described, the pulp must be bleached before the'purifying chemical treatment. This is desirable since those substances which will be oxidized by the oxygen generated in the bleaching reaction, are compounds which are reacted upon by the digesting liquor of caustic potash (KOH), used in our purifying chemical process, and will, therefore, destroy them, leaving an alpha cellulose of 100% of purity. If the bleaching is done after the purifying chemical process, the pulp would suifer a diminution in the amount of its alpha cellulose already obtained because the bleaching reaction is apt to form cxy-celluloses and hydro-celluloses which cannot be eliminated by the following washings, thus causing a degradation in the quality of our cellulose, which would not then reach the 100% of purity obtained through our chemical process. In the case of the electrolytic treatment to be described, the bleaching may take place before or after such treatment.

We have found that using the canes abovementioned, particularly those of the general species known as Anmdo Donax, of which the specific example is Castilla cane, those of the general species known as Gynerium Sagittatum of which the specific example is Brava Cane, and Gynerium Saccharoides and by using the simple process here outlined, that commercially successful quantities of the very highest quality cellulose is obtained. We also have treated other of the canes mentioned with equally satisfactory results.

In referring to Gynerium Saccharoides we mean the hybrid variety, which is obtained by crossing or grafting of the Gynerium Saccharoides with the Arundo Donaxi At this point, we should further reiterate that we may mix various of the canes mentioned above in the digester or we may produce the cellulose from cane or a single variety.

We have found particularly that the alpha terized by a very high degree of purity. Also, the pulp derived from Brava cane possesses exceptional properties; That is to say, that whereas pulps at present available possess one or more beneficial properties to a desirable extent, the present pulp has available all of the various properties required for the manufacture of high grade paper and paper products, as well as cellulose derivatives. In other words, the alpha cellulose, and the pulp produced in accordance with this invention, are new products, in that their properties are not to be found combined in any of the pulps, now available.

We have referred specifically to an electrolytic process for the obtaining of alpha cellulose, and shall now describe the process of obtaining such a product by this method. The cellulose from the digester or the bleached expanded cellulose and in many cases the cellulose which has been subjected to further chemical treatment, is placed in an electrolytic bath.

It is' preferred to expand the cellulose as previously described before it is subjected toan electrolytic treatment.-

By a suitable control of the current, 100% pure alpha cellulose can be deposited. It will be understood that by the use of our electrolytic process the cellulose absolutely pure is polarized in the direction of the electric current, due to the difierence in its conductivity, with respect to the degraded cellulose. In thus treating the cellulose ing down of the fibers and they are recovered with their full strength and in a pure state. This process can be applied also to other pulps, such as wood pulps, rag pulps and mixtures thereof.

It will be understood that the pulp recovered from the digester, with or without the bleaching and expanding process is possessed of a very high percentage of alpha cellulose.

Either purifying treatment may be employed at will, and whether this be accomplished by the chemical methods outlined above or electrolytically, we find that the structure of the cellulose is undisturbed and a pure strong alpha pulp of 100% purity is obtained. If in some cases where because of the nature of the cane, its previous treatment to form the pulp or because of the chemicals employed, the chemical purifying treatment is not satisfactory, we will use the" electrolytic treatment.

The alpha cellulose recovered in accordance with this invention is, of course, useful in the manufacture of paper, parchment, and other fab- 9. After the digestion step above referred to, by

means of one or more of the organic and inor- 15(- f ganic compounds mentioned, or after the washing or purifying steps referred to the short fibers may be separated out in a beater or filter and successfully employed to obtain an insulating material proof against heat and sound. Such material, of course, will be fabricated in any suitable manner, as for example, into boards or sheets.

All of the various products referred to above, are to be considered broadly as paper-like prodnets.

in this specification, we mean alpha cellulose of 100% purity which is not re-acted upon by a solution of sodium hydrate at 26 Be., giving no traces of copper in its analysis nor containing any oxy or hydro-cellulose.

Theelectrolytic bath may comprise any suitable electrolyte, but we have found that success- Iul results are best attained by an electrolytic bath consisting oi. a 6% solution of NaOI-I or 4% solution of NH4OH or 1% solution of NaCl, which do not impair in the least the physical or chemical characteristics of the. fibers. The electrolytic process may be applied to wood pulps, rag pulps 25. and other fiber producing plants, as well as from the bagasse oi the sugar cane and in each case the electrolytic step will separate the pure from the impure, so that 100% pure alpha cellulose will be collected. This application is a continuation in part of the earlier application of Estape, Serial No. 267,806, filed April 5, 1928, Patent No. l,81'l,-

548, August 4, 193i.

We claim:

1. The process or obtaining substantially pure a. alpha cellulose which comprises the step of digesting canes selected from a group consisting of those scientificallylmown as Arundo Donax (Castilla Cane) Gynerium Saccharoides (Carrizo) Gynerium Sagittatum (Brava Cane) Malacca Cane, Otate, Feathergrass, Henequen and Ramie, in an alkaline solution comprising an alkaline hydroxide, sodium sulphide, and ammonia to extract the desired quality of cellulose from the cane under treatment.

2. The process, of obtaining substantially pure alpha cellulose which comprises the step of digesting canes selected from a group consisting of those scientifically known as Arundo Donax (Castilla Cane) Gynerium Saccharoides (Carrizo) Gynerium Sagittatum,;(l3 rava Cane) Malacca Cane, Otate, Feathergrass, Henequen and Ramie, in an alkaline solution comprising an alkaline hydroxide, sodium sulphide, and ammonla to extract the desired quality or cellulose irom the cane under treatment and bleaching the digested cellulose with bleaching compounds selected from a group consisting-o1 acetic acid and calcium hypochlorite.

3. The process of obtaining substantially pure alpha cellulose which comprises the step of digesting canes selected from a group consisting of those scientifically known as Arundo Donax (Castilla Cane) Gynerium Saccharoides (Carrizo) Gynerium Sagittatum (Brava Cane) Malacca Cane,

* Otate, Feathergrass, Henequen and Ramie, in an alkaline solution" comprsing an alkaline hydroxide, sodium sulphide, and ammonia to extract the desired quality of cellulose from the cane under treatment and bleaching the digested cellulose,

by treatment with a solution of caustic" potash and then a treatment with a solution of chloric acid. u y 4. The process or obtaining substantially-pure alpha cellulose which comprises the step or disest- In referring to chemically pure alpha cellulose washing the bleached cellulose and purifying it ing canes selected from a group consisting 01' those scientifically known as Arimdo Donax (Castilla Cane) Gynerium' Saccharoides (Carrizo) Gynerium Sagittatum' (Brava Cane) (Malacca Cane, Otate, Feathergrass, Henequen and Ramie, in an alkaline solution comprising an alkaline hydroxide, sodium sulphide, and ammonia to extract the desired quality of cellulose from the cane under treatment and bleaching the digested cellulose, washing the bleached cellulose and purifying it by treatment with a solution of caustic potash and then a treatment with a solution of chloric acid and washing the cellulose in a solution of ammonia.

5. The process or obtaining substantially pure alpha cellulose which comprises the step of digesting canes selected from a group consisting of those scientifically known as Arundo Donax (Castilla Cane) Gynerium Saccharoides (Carrizo) Gynerium Sagittatum (Brava Cane) Malacca Cane, Otate, Feathergrass, Henequen and Ramie, in an alkaline solution comprising an alkaline hydroxide, sodium sulphide, and ammonia to extract the desired quality of cellulose from the cane under treatment, and electrolytically depositing pure alpha cellulose without destroying the structure or the cellulose.

6. The process or obtaining substantially pure alpha cellulose which comprises the step of digesting canes selected from a group consisting of those scientifically known as Arundo Donax (Castilla Cane) and Gynerium Saccharoides (Carrizo) Gynerium Sagittaturn (Brava Cane) Ma1ac-' ca Cane, Otate, Feathergrass, Henequen and Ramie, in an alkaline solution comprising an alkaline hydroxide, sodium sulphide, and ammonia to extract the desired quality of cellulose from the cane under treatment, bleaching the digested cel lulose, expanding the digested cellulose by blow-, ing with an inert medium, and electrolytically 115 depositingpure alpha cellulose without destroying the structure or the cellulose.

7. The process of obtaining substantially pure alpha cellulose which comprises the step of digesting canes selected from a .group consisting of thosescientifically known as Arundo Donax (Castilla Cane) and Gynerium Saccharoides (Carrizo) Gynerium Sagittatum (Brava Cane) Malacca Cane, Otate, Feathergrass, Henequen and Ramie, in an alkaline solution comprising an alkaline hydroxide, sodium sulphide, and ammonia to extract the desired quality of cellulose from the cane under treatment, bleaching the digested cellulose, washing the bleached cellulose and purifying it by treatment with a solution of caustic potash and then a treatment with a solution or chloric acid, and electrolytically depositing pure alpha cellulose without destroying the structure of the cellulose.

8. The process or preparing substantially pure alpha cellulose which comprises subjecting digested cellulose obtained from the fibers of plants selected froma group consisting oi! those scientifically known as Arundo Donax (Castilla Cane) Gynerium Saccharoides (Carrizo) Gynej rium Sagittatum (Brave Cane) Malacca Cane, Otate, Feathergrass, Henequen and Ramie to electrolytic treatment to separate out substantially pure alpha cellulose,

s. The process of preparing substantially pure alpha cellulose which comprises subjecting (ll-.- gested cellulose obtained from the fibers of plants selected 1mm 9. group consisting of those scientifically known as Arundo Donax (Castilla Cane) Gynerium Saccharoides (Carrizo)-Gynerium Sagittatum (Brava Cane) Malacca Cane, Qtate, Feathergrass, Henequen and Ramie to treatment in an electrolytic bath comprising an alkaline electrolyte without impairing the physical or chemical characteristics of the fibers.

10. The process of obtaining chemically pure alpha cellulose from fibrous material which comprises subjecting the digested fibers to an electrolytic treatment in a bath comprising an alkaline electrolyte which will not destroy the physical or chemical characteristics of the fibers.

11. The process of obtaining chemically pure alpha cellulose from fibrous materials which comprises subjecting the digested fibers to electrolytic treatment in a bath which will not destroy the chemical and physical characteristics of the fibers and comprising an electrolyte selected from a group consisting of NaCl, NH4OH and NaOH.

ANTONIO BAYARTE BORI. JOSE MARTINEZ ESTAPE. 

